Want to know how to block hidden numbers on your iPhone or Android? You can use Do Not Disturb on your iPhone or change the call settings on your Android if you have a Samsung phone. If you don't have a Samsung phone, you can download an app called "Should I Answer?" To block unknown incoming calls on Android. Unfortunately, there is no app or setting available on iPhone that only blocks private, unknown, or restricted calls.
Steps
Method 1 of 3: Block anonymous calls on iPhone

Step 1. Go to your iPhone settings

Press the gray app with 2 cog wheels on it. Usually found on the home screen.

Step 2. Scroll down and press

Do not disturb.
This option is at the top of the settings page.

Step 3. Press the Do Not Disturb switch

It will turn green


Step 4. Select Allow calls from
This option is at the bottom of the screen.

Step 5. Tap All Contacts
Your entire contact list will be added as a Do Not Disturb exception. You will no longer receive calls from people not registered in the Contacts app.
- This method blocks calls from numbers other than those stored in the Contacts application. This means you may miss any calls from potential employers or interview requests.
- Do Not Disturb also prevents notifications from other applications (eg text messages, emails, social networks, etc.) from appearing as an alert.
Method 2 of 3: Block calls on Samsung Galaxy

Step 1. Check the brand of your phone
Samsungs are the only Android phones to offer a setting that rejects anonymous numbers.
If you are using a non-Samsung Android phone, go to the Should I Answer method right away

Step 2. Open the Phone app
Tap the phone-shaped app on your device's main screen.

Step 3. Press ⋮
This option is located at the top right of the screen and opens a drop-down menu.

Step 4. Select Settings
You'll find this option at the bottom of the drop-down menu.

Step 5. Press Number Blocking
This option is in the middle of the menu and opens the call barring settings.

Step 6. Press the Block anonymous calls switch

It will turn blue

and your Samsung will now block all calls from unknown numbers.
Method 3 of 3: Use "Should I Answer" on Android

Step 1. Download Should I Answer
If you already have the application should I answer, skip this step. Otherwise:
- open it
Google play store
- press the search bar
- type should I answer
- select Should I respond?
- Press on TO INSTALL
- choose ACCEPT

Step 2. Open Should I Answer
Press on TO OPEN on the right of the Google Play Store page or tap the Should I Answer app icon in your device's app drawer.

Step 3. Press CONTINUE twice
The 2 options CONTINUE are located at the bottom of the screen and lead to the main page.

Step 4. Open the SETTINGS tab
It's at the top of the main app page.

Step 5. Scroll down to the Block INCOMING calls from section
This section is at the bottom of the page.

Step 6. Press the Hidden Numbers switch

It will change color

which means Should I Answer will block incoming calls from restricted or anonymous numbers.